System and method for controlling hybrid electric vehicle using driving tendency of driver

ABSTRACT

A system and method for controlling a hybrid electric vehicle using a driving tendency are provided. The method includes determining a driving tendency level based on data to determine a driving tendency of a driver and determining a target engine torque using an engine torque map based on a vehicle speed and a required torque. Whether the driving tendency level corresponds to a predetermined level is determined as well as whether the required torque is equal to or greater than a torque that corresponds to an optimal operating point of an engine when the driving tendency level corresponds to the predetermined level. The target engine torque is then adjusted when the required torque is equal to or greater than the torque that corresponds to the optimal operating point of the engine.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2014-0085346 filed in the Korean IntellectualProperty Office on Jul. 8, 2014, the entire contents of which areincorporated herein by reference.

BACKGROUND Field of the Invention

The present invention relates to a system and method for controlling ahybrid electric vehicle. More particularly, the present inventionrelates to a system and method for controlling a hybrid electric vehicleusing a driving tendency of a driver.

Description of the Related Art

As well-known, a hybrid electric vehicle efficiently combines power ofan internal combustion engine and power of a motor and uses the combinedpower to drive the vehicle. The hybrid electric vehicle generallyincludes an engine, a motor, an engine clutch configured to adjust powerbetween the engine and the motor, a transmission, a differential geardevice, a battery, an integrated starter and generator (ISG) configuredto start the engine or generate electric power by an output of theengine, and wheels. The integrated starter and generator may be called ahybrid starter and generator (HSG).

The hybrid electric vehicle provides driving in an electric vehicle (EV)mode in which the power of the motor is used by coupling or decouplingthe engine clutch depending on an acceleration or deceleration intentionbased on a manipulation of an accelerator pedal and a brake pedal by adriver, a vehicle speed, a state of charge (SOC) of the battery, and thelike; a hybrid electric vehicle (HEV) mode in which a torque of theengine is used as main power and a torque of the motor is used asauxiliary power; a regenerative braking mode in which braking andinertial energy are recovered through electric power generation of themotor during braking the vehicle or during driving the vehicle byinertia to be charged in the battery.

Since the hybrid electric vehicle uses both of mechanical energy of theengine and electrical energy of the battery, uses optimal operationregions of the engine and the motor, and recovers the energy at the timeof braking the vehicle, fuel efficiency may be improved, and the energymay be efficiently used. However, a deviation may be generated in fuelefficiency and the SOC of the battery of the hybrid electric vehiclebased on a driving tendency of a driver.

In addition, a satisfaction of the driver associated with drivingperformance of the hybrid electric vehicle depends on whether the hybridelectric vehicle is driven to be appropriate for the driving tendency ofthe driver. However, since the driving tendency of the driver varies,but a performance characteristic of the hybrid electric vehicle is fixedto one performance characteristics with respect to the same vehicletype, a difference may be generated between the driving tendency of thedriver and a reaction of the hybrid electric vehicle. In other words,when the driving tendency of the driver is understood and the hybridvehicle is operated to be appropriate for the driving tendency of thedriver, the satisfaction of the driver associated with the drivingperformance may be maximized.

The above information disclosed in this section is merely forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The present invention provides a method for controlling a hybridelectric vehicle having advantages of optimizing a state of charge (SOC)of a battery and improving fuel efficiency using a driving tendency of adriver.

An exemplary embodiment of the present invention provides a method forcontrolling a hybrid electric vehicle using a driving tendency that mayinclude: determining a driving tendency level based on data to determinea driving tendency of a driver; determining a target engine torque usingan engine torque map based on a vehicle speed and a required torque;determining whether the driving tendency level corresponds to apredetermined level; determining whether the required torque is equal toor greater than a torque that corresponds to an optimal operating pointof an engine when the driving tendency level corresponds to thepredetermined level; and adjusting the target engine torque when therequired torque is equal to or greater than the torque that correspondsto the optimal operating point of the engine.

In the adjustment of the target engine torque, the target engine torquemay be increased up to a part-load max torque of the engine to decreasea motor assist torque. The method for controlling a hybrid electricvehicle using a driving tendency may further include setting a finaltarget engine torque to the torque that corresponds to the optimaloperating point of the engine when the required torque is less than thetorque that corresponds to the optimal operating point of the engine.

Another exemplary embodiment of the present invention provides a methodfor controlling a hybrid electric vehicle using a driving tendency thatmay include: determining a driving tendency level based on data todetermine a driving tendency of a driver; determining whether an idlelock-up charge entering condition is satisfied; and performing an idlelock-up charge control when the idle lock-up charge entering conditionis satisfied, wherein the idle lock-up charge entering condition issatisfied when an engine is in a driven state, the hybrid electricvehicle is in a coasting state, and an SOC of a battery is less than orequal to an idle lock-up charge entering SOC, and the idle lock-upcharge entering SOC is set based on the driving tendency level. In theidle lock-up charge control, an engine clutch may be maintained in anengaged state, and the battery may be charged through electric powergeneration of a motor and an integrated starter and generator.

The method for controlling a hybrid electric vehicle using a drivingtendency may further include: determining whether an idle lock-up chargerelease condition is satisfied; and releasing the idle lock-up chargecontrol when the idle lock-up charge release condition is satisfied,wherein the idle lock-up charge release condition is satisfied when thecoasting state is released or the SOC of the battery is equal to orgreater than an idle lock-up charge release SOC, and the idle lock-upcharge release SOC is set based on the driving tendency level.

Yet another exemplary embodiment of the present invention provides amethod for controlling a hybrid electric vehicle using a drivingtendency may include: determining a driving tendency level based on datato determine a driving tendency of a driver; setting a shift patternbased on the driving tendency level; and performing a shift controlbased on the shift pattern. The driving tendency level may be any one ofa mild level, a normal level, an aggressive level, and a racer level,and the shift pattern may be any one of a mild shift pattern thatcorresponds to the mild level, a normal shift pattern that correspondsto the normal level, an aggressive shift pattern that corresponds to theaggressive level, and a racer shift pattern that corresponds to theracer level. The method for controlling a hybrid electric vehicle usinga driving tendency may further include: setting a creep torque map basedon the driving tendency level; and performing a creep torque controlusing the creep torque map based on a vehicle speed and a shift stage,wherein the shift stage may be determined based on the shift pattern.

Yet still another exemplary embodiment of the present invention providesa method for controlling a hybrid electric vehicle using a drivingtendency that may include: determining a driving tendency level based ondata to determine a driving tendency of a driver; determining whether anengine start condition is satisfied in a state in which an engine isstopped; and performing an engine start control when the engine startcondition is satisfied, wherein the engine start condition may besatisfied when power required by the driver is equal to or greater thana first threshold value, and the first threshold value may be set basedon the driving tendency level.

The engine start condition may be satisfied when accumulated drivingenergy is equal to or greater than a second threshold value, theaccumulated driving energy may be calculated based on required powerduring a predetermined time in a section in which a change rate of aposition value of an accelerator pedal is a positive value, and thesecond threshold value may be set based on the driving tendency level.The method for controlling a hybrid electric vehicle using a drivingtendency may further include: determining whether an engine stopcondition is satisfied in a state in which the engine starts; andperforming an engine stop control when the engine stop condition issatisfied, wherein the engine stop condition may be satisfied when powerrequired by the driver is less than or equal to a third threshold value,and the third threshold value may be set based on the driving tendencylevel.

As described above, according to an exemplary embodiment of the presentinvention, the hybrid electric vehicle may be controlled using thedriving tendency of the driver, thereby making it possible to optimizethe SOC of the battery and improve the fuel efficiency. In addition, theintention of the driver may be more accurately reflected in the shift.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure will now bedescribed in detail with reference to certain exemplary embodimentsthereof illustrated the accompanying drawings which are givenhereinbelow by way of illustration only, and thus are not limitative ofthe present disclosure, and wherein:

FIG. 1 is an exemplary block diagram showing a system for controlling ahybrid electric vehicle according to an exemplary embodiment of thepresent invention;

FIG. 2 is an exemplary flow chart showing a method for controlling anengine torque using a driving tendency according to an exemplaryembodiment of the present invention;

FIG. 3 is an exemplary diagram showing an engine torque map according toan exemplary embodiment of the present invention;

FIG. 4 is an exemplary flow chart showing a method for charging abattery using a driving tendency according to an exemplary embodiment ofthe present invention;

FIG. 5 is an exemplary diagram for describing a method for charging abattery according to an exemplary embodiment of the present invention;

FIG. 6 is an exemplary flow chart showing a method for performing ashift control and a creep torque control using a driving tendencyaccording to an exemplary embodiment of the present invention;

FIG. 7 is an exemplary diagram showing a shift pattern according to anexemplary embodiment of the present invention; and

FIG. 8 is an exemplary flow chart showing a method for performing anengine start control using a driving tendency according to an exemplaryembodiment of the present invention.

DESCRIPTION OF SYMBOLS

-   -   10: engine    -   20: motor    -   30: engine clutch    -   40: transmission    -   50: battery    -   60: integrated starter and generator    -   70: differential gear device    -   80: wheel    -   90: data detector    -   100: controller

DETAILED DESCRIPTION

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g. fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

Although exemplary embodiment is described as using a plurality of unitsto perform the exemplary process, it is understood that the exemplaryprocesses may also be performed by one or plurality of modules.Additionally, it is understood that the term controller/control unitrefers to a hardware device that includes a memory and a processor. Thememory is configured to store the modules and the processor isspecifically configured to execute said modules to perform one or moreprocesses which are described further below.

Furthermore, control logic of the present invention may be embodied asnon-transitory computer readable media on a computer readable mediumcontaining executable program instructions executed by a processor,controller/control unit or the like. Examples of the computer readablemediums include, but are not limited to, ROM, RAM, compact disc(CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards andoptical data storage devices. The computer readable recording medium canalso be distributed in network coupled computer systems so that thecomputer readable media is stored and executed in a distributed fashion,e.g., by a telematics server or a Controller Area Network (CAN).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Hereinafter, exemplary embodiments of the present invention will bedescribed more fully with reference to the accompanying drawings so asto be easily practiced by those skilled in the art to which the presentinvention pertains. In addition, since the respective components shownin the accompanying drawings are arbitrarily shown for convenience ofexplanation, the present invention is not necessarily limited tocontents shown in the accompanying drawings.

FIG. 1 is an exemplary block diagram showing a system for controlling ahybrid electric vehicle according to an exemplary embodiment of thepresent invention. As shown in FIG. 1, the system for controlling ahybrid electric vehicle according to an exemplary embodiment of thepresent invention may include an engine 10, a motor 20, an engine clutch30 configured to adjust power between the engine 10 and the motor 20, atransmission 40, a battery 50, an integrated starter and generator (ISG)60 may be configured to state the engine 10 or generate electric powerby an output of the engine 10, a differential gear device 70, wheels 80,a data detector 90, and a controller 100. The controller 100 may beconfigured to operate the engine 10, the motor 20, the engine clutch 30,the transmission 40, the battery 50, the integrated starter andgenerator (ISG) 60, the differential gear device 70, the wheels 80, andthe data detector 90.

In particular, power generated in the engine 10 or the motor 20 may beselectively transferred to an input shaft of the transmission 40, andpower output from an output terminal of the transmission 40 may betransferred to axles through the differential gear device 70. The axlesmay be configured to rotate the wheels 80, to drive the hybrid electricvehicle by the power generated in the engine 10 or the motor 20. Thebattery 50 may be configured to store a high voltage therein, supply adriving voltage to the motor 20 in an electric vehicle (EV) mode and ahybrid electric vehicle (HEV) mode, and may be charged with electricityrecovered by the motor in a regenerative braking mode.

The controller 100 may be configured to adjust output torques of theengine 10 and the motor 20 based on a state of the hybrid electricvehicle and operate the hybrid electric vehicle in the EV mode, the HEVmode, and the regenerative braking mode based on a driving condition anda state of charge (SOC) of the battery 50. The data detector 90 may beconfigured to detect data to determine a driving tendency of a driver,and the data detected by the data detector 90 may be transferred to thecontroller 100. The data detector 90 may include an accelerator pedalposition sensor 91, a brake pedal position sensor 92, a vehicle speedsensor 93, an SOC sensor 94, an inter-vehicle distance sensor 95, anengine revolution per minute (RPM) sensor 96, and a shift stage sensor97.

The accelerator pedal position sensor 91 may be configured to measure aposition value of an accelerator pedal (e.g., an engagement degree ofthe accelerator pedal) and transfer a signal for the position value tothe controller 100. When the accelerator pedal is completely engaged,the position value of the accelerator pedal may be 100%, and when theaccelerator pedal is disengaged, the position value of the acceleratorpedal may be 0%. A throttle valve opening degree sensor mounted in anintake passage may be used instead of the accelerator pedal positionsensor 91. Therefore, it is to be considered in the presentspecification and the claims that the accelerator pedal position sensor91 may include the throttle valve opening degree detector and theposition value of the accelerator pedal may include an opening degree ofa throttle valve.

The brake pedal position sensor 92 may be configured to measure aposition value of a brake pedal (e.g., an engagement degree of the brakepedal) and transfer a signal for the position value to the controller100. When the brake pedal is completely engaged, the position value ofthe brake pedal may be 100%, and when the brake pedal is disengaged, theposition value of the brake pedal may be 0%. The vehicle speed sensor 93may be configured to detect a vehicle speed and transfer a signal forthe vehicle speed to the controller 100. The vehicle speed sensor 93 maybe mounted within the wheel of the vehicle.

Meanwhile, a target shift stage may be calculated using a shift patternbased on the signal of the accelerator pedal position sensor 91 and thesignal of the vehicle speed sensor 93, and a shift to the target shiftstage may be executed. In other words, for an automatic transmissionthat includes a plurality of planetary gear sets and a plurality offriction elements, hydraulic pressure supplied to the plurality offriction elements or released from the plurality of friction elementsmay be adjusted. In addition, for a double clutch transmission, acurrent applied to a plurality of synchronizer mechanisms and anactuator may be adjusted.

The SOC sensor 94 may be configured to detect the SOC of the battery 50and transfer a signal for the SOC to the controller 100. Instead ofdirectly detecting the SOC of the battery 50, a current and a voltage ofthe battery 50 may be measured, and the SOC of the battery 50 may bepredicted from the measured current and voltage. The inter-vehicledistance sensor 95 may be configured to detect a distance between thehybrid electric vehicle and a preceding vehicle. As the inter-vehicledistance sensor 95, various sensors such as an ultrasonic wave sensor,an infrared sensor, and the like, may be used.

The engine RPM sensor 96 may be configured to detect a revolutions perminute (RPM) of the engine from a phase change of a crank shaft andtransfer a signal for the RPM of the engine to the controller 100. Theshift stage sensor 97 may be configured to detect a shift stagecurrently engaged. The controller 100 may be implemented by at least onemicroprocessor operated by a predetermined program that may include aseries of commands for executing each step included in a method forcontrolling a hybrid electric vehicle according to an exemplaryembodiment of the present invention to be described below.

The controller 100 may be configured to determine a driving tendencylevel of the driver based on the data detected by the data sensor 90.The driving tendency level may be determined based on a driving tendencyindex calculated based on the data. The driving tendency index may becalculated based on how well the plurality of rules associated with thedriving tendency of the driver are satisfied. The plurality of rules maybe predetermined on the assumption that they are considered to beappropriate for those skilled in the art to determine the drivingtendency of the driver. For example, the driving tendency index may becalculated based on the position value of the accelerator pedal, achange rate of the position value of the accelerator pedal, the positionvalue of the brake pedal, a change rate of the position value of thebrake pedal, the vehicle speed, an acceleration, an inter-vehicledistance, a change rate of the inter-vehicle distance, and the like. Thedriving tendency level may be any one of a mild level, a normal level,an aggressive level, and a racer level. Such levels may be predeterminedbased on the above driving tendency index factors. Furthermore, fuelefficiency and the SOC of the battery 50 may deteriorate in a sequenceof the mild level, the normal level, the aggressive level, and the racerlevel. A method of calculating the driving tendency index and a methodof determining the number of driving tendency levels and the drivingtendency level are not limited thereto, by may be variously implementedby those skilled in the art.

The controller 100 may be configured to operate the hybrid electricvehicle based on the determined driving tendency level. In other words,the controller 100 may be configured to adjust the engine torque, adjustthe SOC of the battery, perform a shift control, perform a creep torquecontrol, and perform an engine start control, based on the drivingtendency level. As described above, the hybrid electric vehicle may beappropriately controlled using the driving tendency, thereby making itpossible to improve the fuel efficiency and the SOC of the battery andperform a shift to be appropriate for the driving tendency.

Hereinafter, a method for controlling a hybrid electric vehicle will bedescribed in detail with reference to FIGS. 2 to 8. FIG. 2 is anexemplary flow chart showing a method for controlling an engine torqueusing a driving tendency according to an exemplary embodiment of thepresent invention. FIG. 3 is an exemplary diagram showing an enginetorque map according to an exemplary embodiment of the presentinvention.

As shown in FIGS. 2 and 3, the method for controlling an engine torqueaccording to an exemplary embodiment of the present invention startswith determining the driving tendency level based on the data todetermine the driving tendency of the driver (S110). In other words, thecontroller 100 may be configured to calculate the driving tendency indexbased on the data detected by the data detector 90 and determine thedriving tendency level of the driver based on the driving tendencyindex. The driving tendency level may be any one of the mild level, thenormal level, the aggressive level, and the racer level.

The controller 100 may be configured to set a target engine torque usingan engine torque map based on the vehicle speed and a required torque(S120). The required torque of the driver may be calculated based on theposition value of the accelerator pedal and the vehicle speed, and atarget engine torque that corresponds to a given condition may be storedin the engine torque map. Usually, a torque that corresponds to anoptimal operating point of the engine may be set to the target enginetorque. When the driving tendency level is determined, the controller100 may be configured to determine whether the driving tendency levelcorresponds to a predetermined level (S130). The predetermined level maybe the aggressive level or the racer level, but is not limited thereto.

In response to determining in S130 that the driving tendency level doesnot correspond to the predetermined level, the controller 100 may beconfigured to set the torque that corresponds to the optimal operatingpoint of the engine to a final target engine torque (S160). In responseto determining in S130 that the driving tendency level corresponds tothe predetermined level, the controller 100 may be configured todetermine whether the required torque is equal to or greater than atorque that corresponds to the optimal operating point of the engine(S140). In response to determining in S140 that the required torque isless than the torque that corresponds to the optimal operating point ofthe engine, the controller 100 may be configured to set the torque thatcorresponds to the optimal operating point of the engine to the finaltarget engine torque (S160). In response to determining in S140 that therequired torque is equal to or greater than the torque that correspondsto the optimal operating point of the engine, the controller 100 may beconfigured to adjust the target engine torque (S150). In particular, thecontroller 100 may be configured to increase the target engine torque upto a part-load max torque of the engine. The controller 100 may also beconfigured to set the adjusted target engine torque to the final targetengine torque (S160).

The required torque may be implemented by the sum of the target enginetorque and a motor assist torque. Therefore, when the torque thatcorresponds to the optimal operating point of the engine is set to thetarget engine torque, when the required torque is excessively increased,the motor assist torque may be excessively increased, such that the SOCof the battery 50 may be excessively decreased. When the target enginetorque is output up to the part-load max torque, the motor assist torquemay be decreased. Therefore, an excessive decrease of the SOC of thebattery 50 may be prevented.

FIG. 4 is an exemplary flow chart showing a method for charging abattery using a driving tendency according to an exemplary embodiment ofthe present invention. FIG. 5 is an exemplary diagram describing amethod for charging a battery according to an exemplary embodiment ofthe present invention. As shown in FIG. 4, the method for charging abattery 50 according to an exemplary embodiment of the present inventionstarts with determining the driving tendency level based on the data todetermine the driving tendency of the driver (S210). In other words, thecontroller 100 may be configured to calculate the driving tendency indexbased on the data detected by the data detector 90 and determine thedriving tendency level of the driver based on the driving tendencyindex. The driving tendency level may be any one of the mild level, thenormal level, the aggressive level, and the racer level.

The controller 100 may be configured to determine whether an idlelock-up charge entering condition is satisfied (S220). The idle lock-upcharge entering condition may be considered to be satisfied when theengine 10 is in a driven state, the hybrid electric vehicle is in acoasting state, and the SOC of the battery 50 is less than or equal toan idle lock-up charge entering SOC. The coasting state may bedetermined based on the position value of the accelerator pedal and theposition value of the brake pedal (e.g., degree of engagement ordisengagement). The idle lock-up charge entering SOC may be set based onthe driving tendency level. In other words, an idle lock-up chargeentering SOC based on the aggressive level may be set to be greater thanan idle lock-up charge entering SOC based on the normal level. Inresponse to determining in S220 that the idle lock-up charge enteringcondition is not satisfied, the method for charging a battery using adriving tendency according to an exemplary embodiment of the presentinvention may terminate. In response to determining in S220 that theidle lock-up charge entering condition is satisfied, the controller 100may be configured to perform an idle lock-up charge control (S230).

In the related art, a part-load charge control, an idle charge control,and a power limit control have been performed to charge the battery 50.The part-load charge control is a control used to charge the battery 50by rotating the motor 20 by the power of the engine 10 when theaccelerator pedal is engaged. The part-load charge control is used tomaintain the SOC using residual power of the engine 10 when the vehiclespeed is present in an entire SOC region. The idle charge control isused to charge the battery 50 by rotating the integrated starter andgenerator 60 by the power of the engine 10 regardless of the positionvalue of the accelerator pedal, the position value of the brake pedal,and the vehicle speed to escape from a lowered SOC state. The powerlimit control is used to limit power used in an electronic component toescape from an excessively lowered SOC state.

The idle lock-up charge control is used to charge the battery 50 usingboth of the motor 20 and the integrated starter and generator 60. Whenthe idle lock-up charge entering condition is satisfied, the controller100 may be configured to maintain the engine clutch 30 in an engagedstate and charge the battery 50 through electric power generation of themotor 20 and the integrated starter and generator 60. As shown in FIG.5, since the motor 20 and the integrated starter and generator 60generate the electric power using both of the power of the engine 10 andthe torque of the wheel 80, charge efficiency may be more improved thanthe idle charge control in which only the integrated starter andgenerator 60 is used. Therefore, even when the vehicle is driven under asevere condition in which acceleration or deceleration is frequentlygenerated, the SOC of the battery 50 may be maintained in a normalrange.

Furthermore, the controller 100 may be configured to determine whetheran idle lock-up charge release condition is satisfied (S240). The idlelock-up charge release condition may be considered to be satisfied whenthe coasting state is released or the SOC of the battery is equal to orgreater than an idle lock-up charge release SOC. The idle lock-uprelease SOC may be set based on the driving tendency level. In otherwords, an idle lock-up release SOC based on the aggressive level may beset to be greater than an idle lock-up release SOC based on the normallevel. In response to determining in S240 that the idle lock-up chargerelease condition is not satisfied, the controller 100 may proceed toS230. In response to determining in S240 that the idle lock-up chargerelease condition is satisfied, the controller 100 may be configured torelease the idle lock-up charge control (S250), and terminate the methodfor charging a battery using a driving tendency according to anexemplary embodiment of the present invention.

FIG. 6 is an exemplary flow chart showing a method for performing ashift control and a creep torque control using a driving tendencyaccording to an exemplary embodiment of the present invention. FIG. 7 isan exemplary diagram showing a shift pattern according to an exemplaryembodiment of the present invention. As shown in FIG. 6, the method forperforming a shift control and a creep torque control according to anexemplary embodiment of the present invention starts with determiningthe driving tendency level based on the data to determine the drivingtendency of the driver (S310). In other words, the controller 100 may beconfigured to calculate the driving tendency index based on the datadetected by the data detector 90 and determine the driving tendencylevel of the driver based on the driving tendency index. The drivingtendency level may be any one of the mild level, the normal level, theaggressive level, and the racer level.

The controller 100 may be configured to set a shift pattern and a creeptorque map based on the driving tendency level (S320). As shown in FIG.7, the shift pattern may be set differently based on the drivingtendency level. The shift pattern may be any one of a mild shift patternthat corresponds to the mild level, a normal shift pattern thatcorresponds to the normal level, an aggressive shift pattern thatcorresponds to the aggressive level, and a racer shift pattern thatcorresponds to the racer level. A target creep torque that correspondsto a given condition may be stored in the creep torque map. Creepdriving may refer to that the hybrid electric vehicle is driven by onlythe torque of the motor 20 when the accelerator pedal is disengaged. Thetarget creep torque may be a torque required during the creep driving.

The controller 100 may be configured to perform the shift control basedon the shift pattern (S330). As shown in FIG. 7, a shift may beperformed at a relative lower vehicle speed when the driving tendencylevel is the normal level than when the driving tendency level is theaggressive level. Therefore, a shift feel appropriate for the drivingtendency of the driver may be provided, and when the driving tendencylevel is the aggressive level or the racer level, an average RPM of theengine 10 may increase, thereby making it possible to maintain the SOCof the battery 50 in a normal range. In addition, the controller 100 maybe configured to perform the creep torque control using the creep torquemap based on the vehicle speed and the shift stage. The shift stage maybe determined based on the shift pattern set based on the drivingtendency level. Therefore, the creep torque appropriate for the drivingtendency of the driver may be generated.

FIG. 8 is an exemplary flow chart showing a method for performing anengine start control using a driving tendency according to an exemplaryembodiment of the present invention. As shown in FIG. 8, the method forperforming an engine start control according to an exemplary embodimentof the present invention starts with determining the driving tendencylevel based on the data to determine the driving tendency of the driver(S410). In other words, the controller 100 may be configured tocalculate the driving tendency index based on the data detected by thedata detector 90 and determine the driving tendency level based on thedriving tendency index. The driving tendency level may be any one of themild level, the normal level, the aggressive level, and the racer level.

The controller 100 may be configured to determine whether an enginestart condition is satisfied when the engine is stopped (S420). Theengine start condition may be considered to be satisfied when powerrequired by the driver is equal to or greater than a first thresholdvalue. The power required by the driver may be calculated based on therequired torque and the vehicle speed, and the first threshold value maybe set based on the driving tendency level. In other words, a firstthreshold value based on the aggressive level may be set to be less thana first threshold value based on the normal level.

In addition, the engine start condition may be considered to besatisfied when accumulated driving energy is equal to or greater than asecond threshold value. The accumulated driving energy may be calculatedbased on the required power during a predetermined time in a section inwhich a change rate of the position value of the accelerator pedal is apositive value. The second threshold value may be set based on thedriving tendency level. In other words, a second threshold value basedon the aggressive level may be set to be less than a second thresholdvalue based on the normal level.

In response to determining in S420 that the engine start condition isnot satisfied, the method for performing an engine start control using adriving tendency according to an exemplary embodiment of the presentinvention may terminate. In response to determining in S420 that theengine start condition is satisfied, the controller 100 may beconfigured to perform the engine start control (S430). A mode of thehybrid electric vehicle may be converted from the EV mode into the HEVmode based on the engine start control.

Furthermore, the controller 100 may be configured to determine whetheran engine stop condition is satisfied (S440). The engine stop conditionmay be considered to be satisfied when power required by the driver isless than or equal to a third threshold value. The third threshold valuemay be set based on the driving tendency level. In other words, a thirdthreshold value based on the aggressive level may be set to be greaterthan a third threshold value based on the normal level. In response todetermining in S440 that the engine stop condition is satisfied, thecontroller 100 may be configured to perform an engine stop control(S450) and terminate the method for performing an engine start controlusing a driving tendency according to an exemplary embodiment of thepresent invention.

As described above, according to an exemplary embodiment of the presentinvention, the hybrid electric vehicle may be controlled using thedriving tendency of the driver, thereby making it possible to optimizethe SOC of the battery 50 and improve the fuel efficiency. In addition,the intention of the driver may be more accurately reflected in theshift.

While this invention has been described in connection with what ispresently considered to be exemplary embodiments, it is to be understoodthat the invention is not limited to the disclosed exemplaryembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1.-9. (canceled)
 10. A method for controlling a hybrid electric vehicleusing a driving tendency, comprising: determining, by the controller, adriving tendency level based on data to determine a driving tendency ofa driver; determining, by the controller, whether an engine startcondition is satisfied in a state in which an engine is stopped; andperforming, by the controller, an engine start control when the enginestart condition is satisfied, wherein the engine start condition issatisfied when power required by the driver is equal to or greater thana first threshold value, and the first threshold value is set based onthe driving tendency level.
 11. The method for controlling a hybridelectric vehicle using a driving tendency of claim 10, wherein theengine start condition is satisfied when accumulated driving energy isequal to or greater than a second threshold value, the accumulateddriving energy is calculated based on required power during apredetermined time in a section in which a change rate of a positionvalue of an accelerator pedal is a positive value, and the secondthreshold value is set based on the driving tendency level.
 12. Themethod for controlling a hybrid electric vehicle using a drivingtendency of claim 10, further comprising: determining, by thecontroller, whether an engine stop condition is satisfied in a state inwhich the engine starts; and performing, by the controller, an enginestop control when the engine stop condition is satisfied, wherein theengine stop condition is satisfied when power required by the driver isless than or equal to a third threshold value, and the third thresholdvalue is set based on the driving tendency level. 13.-18. (canceled)